Switches controlled by MCU

Discussion in 'The Projects Forum' started by drevilz, Dec 19, 2013.

  1. drevilz

    Thread Starter New Member

    Feb 13, 2013
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    Hi,

    I am doing a project that consists of a high voltage op amp (low current) that I am using as a source. I need to divide this source into six independent channels that can be controlled as on or off using a microcontroller.

    I would like to know if there is an IC that can handle this kind of voltage and have a quick switching speed. i prefer having an IC since it takes up less space in my project.

    Thanks
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Details please. "High" voltage means nothing without numbers. And it's not clear what you mean about dividing a single op-amp output into 6 channels. Do you mean you want 6 channels that, when on, have the same voltage as the op-amp output, but can be turned off independently?
     
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
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  4. drevilz

    Thread Starter New Member

    Feb 13, 2013
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    Sorry I thought I put the number. Maximum voltage is 250 volts and maximum current is 10ma.
     
  5. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    250 volts dc?
     
  6. drevilz

    Thread Starter New Member

    Feb 13, 2013
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    I will be using it as a square wave or triangle wave with a duty cycle of 4 to 11% with a frequency of 50 to 100 hz. It has bipolar capabilities, but for now I will be using it from 0 to about 150 volts.

    Thanks
     
  7. drevilz

    Thread Starter New Member

    Feb 13, 2013
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    And yes, I mean having six channels with identical voltages from the op amp.
     
  8. wayneh

    Expert

    Sep 9, 2010
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    What sort of load is expected on the 6 channels? Not much I guess, if the op-amp is only supply 10mA.

    If you route the op-amp output through a 1k or 10kΩ resistor, one for each channel, then you could use a small, high voltage MOSFET to either do nothing (off, non-conducting) or ground the signal (on, conducting to ground). The state of the 6 MOSFETs would be determined by the voltage on their gates.

    Would that do it?
     
  9. drevilz

    Thread Starter New Member

    Feb 13, 2013
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    Yes this would work. I would prefer having an IC do this just because it takes up less space, but if I can't find one then I might have to settle for transistors.

    Thanks.
     
  10. mehmeter3

    New Member

    Dec 19, 2013
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    These are new questions and I apologize for posting them here but I couldn't do it using my account. I will appreciate if you could help me with the following:

    Thank you/Red

    1) When using high voltage supplies, safety requirements dictate that a safety ground has to be connected between the HV supply ground terminal and a building ground. However, this creates a ground loop, with ground currents flowing through ground screens in the signal cables between the control unit and the HV supply. How can these ground currents be minimized?

    2) Sketch an amplifier circuit for measuring currents up to 1 μA from DC to 1 kHz. Input impedance shall be lower than 100 Ω. Output voltage at 1 μA shall be 1 V.
     
  11. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Normally all earth grounds are taken to a central star point earth ground plate or connection, including any shields and any and all metallic objects associated with the circuit.
    This prevents any ground loops.
    Max.
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,090
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    You might be able to find a transistor array that can do it. The common ULN2803A cannot handle the voltage but perhaps there are other options.
     
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